This invention relates generally to photographic film development machinery, and in particular to a photographic film development machine which is especially well adapted to developing films which are relatively small in length and width, and which is capable of utilization in areas of limited access.
Machines are known which are capable of transporting a web or strip of film through a series of roller racks which extend into various tanks containing various film treatment baths therein. Such racks are capable of automatically transporting the film being developed through a series of areas for development, drying and subsequent delivery from the machine.
In order to increase the reliability of such machines, the various patent applications and issued patents above described have disclosed roller racks having rollers which are sufficiently close together to safely guide a strip or web of film therethrough, without the film jamming within the transport rack as a result of its failure to properly thread between respective rollers within the rack.
These roller and gear systems have operated satisfactorily in transporting a web of film through the machine both safely and with assured reliability. However, in certain applications, the film being developed is not found in long narrow strips or webs but rather is short and rectangular in shape; possibly even a single frame of relatively small size. One example of such a film would be the dental x-ray, which is ordinarily of a size on the order of one square inch. In developing films of this size there arises problems different from those problems addressed and solved in connection with roller racks which are capable of processing long strips of film.
For example, the small size of the films to be developed makes it more difficult to assure proper threading of the films through the various transport roller racks of the film development machine. Particular care must be taken when the film is to be caused to turn through a given angle of rotation, to either change the direction in which the film is proceeding, or to pass that film from one area of the machine to another.
In addition, unlike the larger web developing machines, having large racks and which are best suited to larger commercial utilization, machines capable of developing smaller films must be able to accommodate potential small scale, private users. For example, in the processing of relatively small x-rays, such as dental x-rays, the potential user would be a laboratory or even a private practitioner. A developing machine which will be useful in such situations must therefore account for the potential environment in which it is to be used.
First, such a machine must be sufficiently small to acceptably fit into the laboratory or office in which it is to be used. Most such facilities cannot afford to have such a machine occupying a significant amount of floor space. It would therefore be preferable to have a film development machine which is capable of resting upon a table top and which is capable of use in areas having limited access space.
Second, such a machine should be sufficiently simple in operation that a person not well skilled in the art of film development can operate the machine and obtain proper results.
Film development machines which have been devised to satisfy the foregoing requirements have been less than satisfactory in their performance. Producing a film development machine which is small in size has required the use of roller racks which have short, shallow paths along which a film is caused to travel, to enable such roller racks to fit into the small film treatment tanks available, rather than the long, linear paths which can be used in larger development machines. Consequently, a film to be developed is able to pass through a given film treatment tank along a significantly shorter path. However, to properly develop a film, it is necessary that it remain within each film treatment tank for a specified period of time to assure complete development. Since this period of time is fixed, previous film development machines have had to process a film through the several roller racks at a slow rate of speed, to compensate for the short length of the path of film travel through each film treatment tank.
Slowing down the rate of speed that a film travels through a series of rollers causes certain problems to arise. First, a film when wet is limp in consistency. Consequently, there arises the potential that a limp film, while being passed from roller to roller, will have sufficient time to curve downwardly, causing that film to leave its prescribed path. Second, a film during the drying process tends to curl, as well as to stick to the rollers as it is passed therethrough. Again the opportunity exists for a film to leave its prescribed path of film travel. In either case, the film being processed would be damaged, if not completely destroyed. Moreover, these problems become even more acute when the films being processed are small in length and width.
In order to reduce this potential for damage to a film, there arises a need for a film development machine which is small in size, yet which is capable of fully developing a film while also processing that film therethrough along a path of film travel which is more conducive to proper film threading.